By bus
Buses are the most practical way to travel between Bulgarian cities. Private companies fill in where trains are slow or infrequent, with frequent departures on the Sofia–Plovdiv, Sofia–Varna, and Sofia–Burgas corridors. Tickets are cheap — a Sofia–Plovdiv bus (about 2 hours) costs around €5–7. Buy tickets at the bus station; advance booking is wise in summer for coastal routes. The website avtogari.info lists most domestic services.
By train
BDZ (Bulgarian State Railways) covers the main cities but trains are often slower than buses and schedules can be sparse. The scenic Rhodope narrow-gauge line from Septemvri to Dobrinishte is worth taking for the ride itself. For longer cross-country routes, the overnight train can be a reasonable option if you want to save on accommodation. Book at bdz.bg.
By car
Renting a car unlocks a lot of Bulgaria that's otherwise hard to reach — mountain villages, monastery trails, and the quieter stretches of the Black Sea coast. Roads between major cities are mostly good; secondary roads vary considerably. Drive carefully on mountain passes, especially in autumn and winter. International driving licences are accepted. Fuel is cheaper than in Western Europe. Speed cameras are common on main roads.
In cities
Sofia has a metro, trams, and buses, all on a single ticket system. Taxis are inexpensive — use the metered ones or apps like Bolt to avoid inflated tourist rates. Plovdiv and Varna are both compact enough to walk most things.